In this sheet, the numbers are actually text.
I tried Format->Number then Number, Percent and Scientific, and they still appear as text.
As experiments: I cannot add 1 to these, and I cannot pass them to the
value() function. They do not have an apostrophe at the beginning, which would make them text.
How can I format these numbers as numbers?
I deleted the link to the sheet, because the excess character (which I identified as the cause) mysteriously disappeared from the sheet as well as historical versions which in principle are immutable! See answer below.